fix(module:select): display error when in tag and search mode

[wenqi73]

PR Checklist

Close #3424

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/NG-ZORRO/ng-zorro-antd/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[x] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] Application (the showcase website) / infrastructure changes
[ ] Other... Please describe:

What is the current behavior?

Issue Number: N/A

What is the new behavior?

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

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[codecov]

Codecov Report

Merging #3442 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff            @@
##           master   #3442      +/-   ##
=========================================
+ Coverage    95.6%   95.6%   +<.01%     
=========================================
  Files         609     609              
  Lines       13250   13256       +6     
  Branches     1810    1814       +4     
=========================================
+ Hits        12668   12674       +6     
  Misses        197     197              
  Partials      385     385

Impacted Files	Coverage Δ
components/select/nz-select.service.ts	86.78% <100%> (+0.35%)	⬆️

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